1. Field of the Invention
The present invention relates generally to medical devices and methods. More particularly, the present invention relates to apparatus and methods for delivering stents and other luminal prostheses to bifurcations in the vasculature and other body lumens.
Stenting is a common medical procedure used in the vasculature and other body lumens. Over the last decade, the use of stents and other vascular prostheses has become wide spread in the revascularzation of stenotic blood vessels where the blood vessel is first dilated and a stent placed to maintain vessel patency following the procedure. The stents are typically small, mesh-like tubular devices which are expanded in situ. They are typically formed from a metal and can be coated with drugs or other active agents.
The use of stents, and in particular drug-coated stents, has been very successful in the treatment of many forms for coronary artery disease. The success of stents, however, has been more limited for the treatment of lesions occurring at vessel bifurcations. While the disease in the main vessel is generally treated successfully, the outcome in the smaller or “side branch” vessel is often less successful. The lack of success is believed to result from a lack of coverage by the stent at the ostium (opening) of a lesion and the resulting lack of drug delivery to that area.
To overcome at least some of these shortcomings, the inventors herein have developed a stent having a self-opening side portion which covers the side branch ostium when the stent is opened in the main blood vessel or other body lumen. This stent is described in co-pending application Ser. No. 11/330,382, filed on Jan. 10, 2006, the full disclosure of which is incorporated herein by reference.
Stents having side holes or openings for alignment with side branch lumens are generally known in the art, and a variety of protocols and systems for delivering such stents to vascular and other luminal bifurcations are known. Of particular interest of the present invention, several guidewire systems have been proposed for delivering such stents to a luminal bifurcation and for aligning the side hole with a side branch ostium prior to expansion of the stent. For example, U.S. Pat. No. 5,749,825 to Fischell et al. describes introducing a balloon catheter carrying the stent over a main vessel guidewire. A side branch tube is positioned beneath a proximal portion of the stent and over the exterior of the balloon. A distal portion of the side branch tube extends through a side hole in the stent and permits advancement of a side branch guidewire into the side branch vessel. While generally effective for aligning the side hole of the stent with the side branch, the unconstrained distal portion of the side branch tube which extends from the side hole can interfere with advancement of the catheter through the vasculature. The presence of the side branch tube can increase the profile of the catheter, thus making it more difficult to introduce to smaller blood vessels and body lumens. Finally, Fischell suggests no specific approach for assuring that the two guidewires have not become crossed at the bifurcation so that the side hole is misaligned with the side branch ostium.
A similar stent and catheter structure is described in U.S. Pat. No. 6,048,361, to Von Oepen. The guidewire tube of the '361 patent (referred to as a “hollow chamber”), however, is shown to extend to the center of the side opening in the stent. While this reduces the likelihood that the guidewire tube will interfere with catheter advancement, the chance of such interference is not completely eliminated. The distal tip of the guidewire tube (hollow chamber) remains exposed through the side hole and can potentially impede advancement of the catheter.
Other patents showing the use of side tubes for delivering stents having side holes to bifurcated body lumens include U.S. Pat. Nos. 6,099,497; 6,165,195; and 6,596,020, and various related patents and publications.
Attempts have been made to design a dedicated stent for bifurcation lesions. These stents are designed to support and deliver drugs to at least part of the bifurcation area.
However, current solutions usually require two balloons, two sheaths and two guide wires to facilitate both alignment and expansion of the stent.
These solutions suffer from a variety of shortcomings. One example of such shortcoming is high profile and cumbersome delivery system relative to conventional stents, resulting in difficult delivery through tortuous anatomy and through tight lesions. It creates a need for aggressive predilation that causes trauma to the vessel.
Another example of such shortcoming is due to the need for accurate axial and rotational positioning of the stent facing the side branch. These devices are mostly “self aligning,” meaning that the stent is pushed to its axial position by the physician while rotational orientation is dictated by the side sheath. These devices do not provide indication for rotational orientation and do not provide the physician with means to torque the stent into position. Occasionally the high profile of these devices causes friction between the device and the lesion and may prevent the stent from aligning properly. Without means to torque the stent into position and without indication of proper position, the stent may be expanded with the side access facing the vessel wall instead of facing the side branch.
For these reasons, it would be desirable to provide improved apparatus, systems, and methods for delivering stents and other prostheses to bifurcated vasculature and other body lumens. In particular, it would be desirable to provide for the delivery of stents having a side opening such that the side opening is properly aligned with the ostium of a side branch lumen prior to expansion of the stent or other prostheses. It would be still more desirable if the delivery systems were compatible with stents having self-opening side structures in which to find the side opening in the stent. Such devices, systems, and methods should be compatible with small diameter (low profile) catheter structures, should reduce or eliminate any structure which exposed at or through the side openings in the stent or prostheses, and should allow for conformation of proper positioning of the side hole prior to expansion of the stent or other prostheses. At least some of these objectives will be met by the inventions described herein below.
2. Description of the Background Art
Patents and published applications describing bifurcated stents and delivery systems include U.S. Pat. Nos. 4,994,071; 5,609,627; 5,749,825; 5,755,735; 5,928,248; 6,048,361; 6,099,497; 6,165,195; 6,221,098; 6,210,429; 6,325,826; 6,596,020; 6,599,316; 6,676,691; 6,682,536; 6,689,156; 6,692,483; 6,709,440; 6,706,062; 6,835,203; 6,884,258; U.S. Publication Nos. 2002/0042650; 2002/0156516; 2002/0173835; 2003/0187494; 2003/0195606; 2004/0015227; 2004/0019302; 2004/0133268; 2004/0138737; 2005/0010278; 2005/0015108; 2005/0060027; 2005/0102,019; 2006/0036315; EP 1 2554 506 B1; and German Patents DE 297 08 803 U1; and DE 29 701 758 U1.